Corrugated coaxial cable

ABSTRACT

A connector is disclosed for use with coaxial cable of a type having a rigid armoring sheath which is corrugated and which surrounds a coaxial outer conductor and an inner conductor supported along the center of the cable with dielectric material. The connector includes a one-piece outer conductive shell which is crimped down directly onto the armoring sheath of the cable at its ends and an inner contact structure comprised of a sleeve crimped onto the center conductors of the ends of cables and supported within the outer shell by dielectric inserts. The outer shell has an undeformed inner diameter sufficient to pass over the outside of the armoring sheath for installation of the inner contact structure prior to a final positioning of the outer shell and crimping thereof onto the cable. The outer shell is not much larger in maximum diameter than that of the cable and is relatively smooth to facilitate multiple usage in coaxial tubes carrying twenty or more coaxial cables.

United States Patent [72] Inventors Michael Francis O'Keel'e PrimaryExaminer-Darrell L. Clay Mechanicsburg; Attorneys-Curtis, Morris andSafford, Marshall M. Edgar Wilmont Forney, Jr., Harrisburg, l-lolcombe,William l-lintze, William J. Keating, Frederick Pa. R. Raring, John R.Hopkins, Adrian J. La Rue and Jay L. [21] Appl. No. 829,364 Seitchik[22] Filed June 2, 1969 [45] Patented Feb. 23 1971 [73] Asslgnee azg sfigg ABSTRACT: A connector is disclosed for use with coaxial cable of atype having a rigid armoring sheath which is corrugated and whichsurrounds a coaxial outer conductor and an 54 CORRUGATED COAXIAL CABLEinner conductor supported along the center of the cable with 4 Chims, 5Drawing Figs dielectric material. 'lhe connector includes a one-pieceouter conductive shell which is crlmped down directly onto the ar- U-S-Clmoring sheath of the cable at ends and an inner onta t 339/276structure comprised of a sleeve crimped onto the center con- [51] Int.Cl. H02g 15/02 m f the ends f cables and Supported within the outer 8l5/08 shell by dielectric inserts. The outer shell has an undeformed IFleld of Search inner diameter uffi ient to pass over the outside of thearmor. 91; 339/177, 276; 29/62 ing sheath for installation of the innercontact structure prior to a final positioning of the outer shell andcrimping thereof [56] References Cited onto the cable. The outer shellis not much larger in maximum UNITED STATES PATENTS diameter than thatof the cable and is relatively smooth to 2,889.394 6/ 1959 Aunel74/88(.2) facilitate multiple usage in coaxial tubes carrying twenty or3,502,788 3/1970 Albert 174 /88( .2) more coaxial cables.

2 I I l I II I I i I I I l l I I I i I I J l I i 'lw' |.l!| i I i 1 I il |22e|2 t" .--'|i A PATENTEU FEB23197| sum 2 or 2 coriaucATsn cor.CABLE BACKGROUND OF THE INVENTION Frequency space limitation is forcingthe telephone industry to change from microwave space transmission tocoaxial cable transmission with most cables being placed underground.One cable developed for such use includes a center conductor of solidcopper held by discs or spirals of dielectric material within anoutercopper conductor, all surrounded by a rigid, corrugated sheath. Cablesof this construction are combined in ten or more pairs within a heavymetal tube laid underground. Cable systems made of such tubes areextended for hundreds of miles underground with amplifiers located everyseveral miles to maintain an adequate signal level. The development ofcoaxial cable which is mechanically strong to maintain concentricity andefficient signal transfer in underground usage coupled with the factthat many thousands of miles of individual cable must be laid havingtens of thousands of joints has, in turn, created a need for a connectorwhich is mechanically and electrically compatible with the cable butwhich is inexpensive and can be applied quickly and reliably in thefield. Additionally, the connector for such use must be compact so as tobe employed in multiple within a protective joint of limited size.

SUMMARY or THE INVENTION The present invention relates to a coaxialconnector for coaxial cable having a rigid corrugated protective sheathand particularly to a coaxial splice capable of carrying communicationsignals of appreciable frequency with minimum loss and signalreflection. V

It is the object of the present invention to provide a coaxial devicefor splicing coaxial cables quickly and reliably in the field. It isanother object to provide coaxial cable splice techniques which can beaccomplished in the field with a minimum requirement of skill. It isstill another object to provide a coaxial splice for use with corrugatedcoaxial cable of a type used by the telephone industry.

The foregoing objects are obtained by the present invention through theuse of a connector which had only two parts which must be handled tointerconnect the ends of corrugated coaxial cable. One part forms acenter contact structure and is comprised of a malleable metal sleevewith dielectric inserts affixed to each end. The other part is aone-piece malleable metal shell internally dimensioned to slide over acable end so as to permit the center contact structure to be crimpedonto the center conductors of the cable with the shell then beingpositioned over the outer sheath of the cable ends and crimped directlyonto the corrugated sheath of the cable. The crimp employed deformsportions of the outer shell in a corrugated fashion to match up with thecorrugation of the sheaths and provide a mechanical and an electricaljoining of the cable ends.

in the drawings:

P10. 1 is a perspective view of a tube containing a plurality of coaxialcables interconnected by coaxial connector splices in accordance withthe invention; I

FIG. 2 is a view of an individual splice as shown in FIG. 1 butconsiderably enlarged;

FlG. 3 is a perspective and exploded view of the coaxial splice of FIGS.1 and 2 separated from dressed coaxial cable ends;

FIG. 4 is a longitudinal view in partial section of a splice inaccordance with the invention as terminated to corrugated coaxial cableends and further showing to the left dies in the process of deformingthe outer shell against the corrugated sheath of the cable; and

FIG. 5 is a perspective view of a tool carrying the dies shown in FIG.

Referring now to FIG. 1, T represents a tube of a type laid undergroundto form part of a coaxial cable system. Tube T is typically comprised ofa lead shell L lined and covered with a protective plastic S. Tube Ttypically contains ten pairs of coaxial cables 10 and in addition anumber of individual electrical leads. Cables 10 are joined by splices16 within a protective joint J interconnecting the ends of tubes T.Tubes T containing lengths of cables and leads are installed in a trenchwith the cable ends being terminated when necessary according to thelength thereof. This is typically done in the field and in the trench.Alternatively, splices are made adjacent to the trench with completedjoints being then lowered into the trench.

The individual cables 10 are shown in FIGS. 2 and 3 comprised of a solidcenter conductor 12 concentrically mounted within an outer conductor 14which is secured within a corrugated protective sheath 15. The centerconductor 12 is supported concentrically of the outer conductor bydielectric discs fitted within the outer conductor or in certainconstructions by dielectric material extending spirally along the lengthof the cable and wrapped around the center conductor. A typical cablehas a solid copper center conductor 12 approximately 0.100 of an inch indiameter with dielectric discs approximately 0.085 of an inch thickformed of polyethylene material spaced every inch along the cable. Theouter conductor 14 is 0.004 of an inch copper sheet material formed intoa tubular configuration and bonded to the outer sheath 15 which is atin-plated steel 0.010 of an inch having a soldered butt-lap seam. Theresulting cable structure is quite rigid.

FIGS. 1, 2 and 4 show a splice version 16 of the invention terminatingthe ends of cables 10. This termination is designed to mechanically jointhe cable ends and to electrically join the inner and outer conductiveportions of the cable so as to provide a transmission path for signalscarried by the cables. As shown in FIGS. 3 and 4, the invention splice16 is comprised of essentially two parts, an outer conductive shell 18and an inner contact structure 24. The inner contact structure 24includes a hollow sleeve 26 of a reduced diameter at each end 28 whichis fitted within a dielectric support element 32. Support elements 32each include an inner bore 34 which receives 28 and a pair of ports 36are included to provide passage for gas in the event the cables arepressurized. The support elements 32 are locked to sleeve 34 by.flairing end portions 28 after the elements have been mounted on thesleeve.

The outer shell 18 is comprised of a one-piece. element formed of sheetmetal into a tubular configuration having a seam shown as 20 in FIG. 3.Seam 20 is preferably brazed or otherwise jointed to make the pieceintegral. At each end of 18 is a portion 22 of reduced diameter. Theinterior diameter of 22, shown as D, is just large enough to fit overthe outside of protective sheath 15 of the cable. FIG. 3 shows, to therighthand side, the end portion 22 of a shell 18 positioned over a cableend preparatory to termination.

In terminating the cable a portion of the outer conductor 14 and thesheath 15 is first removed to expose a portion of the center conductor12, as shown in FIG. 3. The center contact structure 24 is then placedin position with the center conductors 12 of each cable end insertedtherein. Sleeve 26 is then crimped inwardly in the manner shown in FIG.4 to permanently join the sleeve to the center conductors 12. This maybe done by any suitable crimping tool in a standard manner. Next theshell 18 is slid over the center conductor structure to the positionshown in FIG.'4 with portions 22 then deformed inwardly as by crimpingtomechanically and electrically connect the shell to the cable outersheath 15. A tool 40 used to effect both outer crimps is shown inperspective in FIG. 5 and in place in FIG. 4. The tool should include asuitable straight action driving mechanism, a variety of which areavailable in both handand bench-mounted versions. The tool includes anindexing blade 42 which in use is centered within the valley of acorrugation of 15 properly spaced from a cable end. With 42 sopositioned, the crimping dies shown in 44 and 46 are then properlyaligned in accordance with the remaining corrugations on a cable end.The shell 18 is then worked over the cable end toward 42 and the tool isthen operated to drive the dies 44 and 46 relatively together to deformportion 22 of shell 18 inwardly and into the corrugations of 15. Thetool is then reversed with the other portion 22 crimped inwardly toterminate the other cable end.

As can be discerned from FIG. 4, the die surfaces are bladelike toresult in a series of indentations bringing the metal of 22 into anintimate surface deforming engagement with 15 without crushing thesheath or outer conductor 14. The indexing blade 42 is secured to thefixed dies 44 and is extended inward of the die surface to facilitatecable alignment.

The center region of the outer shell 18 is appropriately enlarged bystandard design techniques in order to compensate for the increase indiameter of the center contact sleeve 26 which would otherwise adverselyaffect the characteristic impedance of the connector in this'region. Theouter surface of 18 is smooth and not much larger than the cable tofacilitate packaging in the manner shown in FIG. 1. 1 In brief summary,it will be observed that the splice in the invention includes only twoparts which must be physically handled with both parts being ofa'configuration to be readily installed by hand in the field. It will befurther observed that the terminating procedure is simple andstraightforward.

In an actual embodiment of the invention splice sleeve 26 was formed ofan annealed copper 0.025 of an inch in wall.

thickness, the insert supports 32 were ofpolyethylene and the outershell 18 was of annealed copper of 0.020 of an inch in wall thickness.Elements 26 and 18 were both tin plated. A termination like that shownin FIG. 4 was tested mechanically and electrically. It was found thatthe termination of the center conductors was adequateto prevent centerconductor displacement and that the overall termination was capable ofstanding a tensional load of in excess of 600 pounds, in excess of 300pounds individually for the center contact and for the outer sleeve. Theresulting connection was found to pass signal frequencies withoutappreciable loss or reflection in excess of 2300 MHz. j'.

Having now disclosed the invention'in terms intended to enableapreferred practice thereof, claims are appended which are believed todefine what is inventive.

We claim:

1. A coaxial electrical connection comprising: a coaxial cable having aninner conductor and an outer conductor and a sheath including sheetmetal having annular corrugations therein to provide a rigid tubularstructure, a connector mechanically and electrically secured to saidcable and including an inner contact element terminated to the cableinner conductor and an outer conductive member terminated to the cableouter conductor, said outer conductive member comprising a shell ofmalleable metal including a tubular end portion extended over andreceiving therein the cable protective sheath, said end portion beingcrimped inwardly against said protective sheath forming a series ofindentations of a configuration overlying and corresponding to theconfiguration of said corrugations around the periphery of saidprotective sheath, said outer member having an outer diameter not muchgreater than the outer diameter of said protective sheath.

2. The connection of claim 1 wherein said shell is comprised of onepiece of sheet metal formed into tubular configuration.

3. A splice between coaxial cables each of the type having an innerconductor, an outer conductor and an outer protective sheath formed ofcorrugated sheet metal, comprising: two component parts, one of saidparts being comprised of a center contact element including a sleeve ofmalleable metal receiving and joining together the center conductors ofa pair of said coaxial cables and crimped inwardly in electrical andmechanical connection with said center conductors, said one of saidparts including further a dielectric element positioned on each end ofsaid sleeve and engaged against an end of a sheath and outer conductorof a corresponding one of the pair of said coaxial cables, the other ofsaid parts being comprised of a shell of malleable metal including ateach end a tubular portion received over and crimped inwardly directlyagainst the protective sheath of each of said coaxial cables, said shellbeing comprised of sheet metal with a series of deformations in saidtubular portion, said series overlying said protective sheath of each ofsaid coaxial cables and of a configuration corresponding to that of thecorrugations of said protective sheaths.

4. The splice of claim 3 wherein, said one part consists of said sleevewith said dielectric elements being secured to the ends of said sleeveand in radial-spaced relationship with respect to said shell, and saidshell consists of a one-piece metal tubular element.

1. A coaxial electrical connection comprising: a coaxial cable having aninner conductor and an outer conductor and a protective sheath extendedover said outer conductor, said sheath including sheet metal havingannular corrugations therein to provide a rigid tubular structure, aconnector mechanically and electrically secured to said cable andincluding an inner contact element terminated to the cable innerconductor and an outer conductive member terminated to the cable outerconductor, said outer conductive member comprising a shell of malleablemetal including a tubular end portion extended over and receivingtherein the cable protective sheath, said end portion being crimpedinwardly against said protective sheath forming a series of indentationsof a configuration overlying and corresponding to the configuration ofsaid corrugations around the periphery of said protective sheath, saidouter member having an outer diameter not much greater than the outerdiameter of said protective sheath.
 2. The connection of claim 1 whereinsaid shell is comprised of one piece of sheet metal formed into tubularconfiguration.
 3. A splice between coaxial cables each of the typehaving an inner conductor, an outer conductor and an outer protectivesheath formed of corrugated sheet metal, comprising: two componentparts, one of said parts being comprised of a center contact elementincluding a sleeve of malleable metal receiving and joining together thecenter conductors of a pair of said coaxial cables and crimped inwardlyin electrical and mechanical connection with said center conductors,said one of said parts including further a dielectric element positionedon each end of said sleeve and engaged against an end of a sheath andouter conductor of a corresponding one of the pair of said coaxialcables, the other of said parts being comprised of a shell of malleablemetal including at each end a tubular portion received over and crimpedinwardly directly against the protective sheath of each of said coaxialcables, said shell being comprised of sheet metal with a series ofdeformations in said tubular portion, said series overlying saidprotective sheath of each of said coaxial cables and of a configurationcorresponding to that of the corrugations of said protective sheaths. 4.The splice of claim 3 wherein, said one part consists of said sleevewith said dielectric elements being secured to the ends of said sleeveand in radial-spaced relationship with respect to said shell, and saidshell consists of a one-piece metal tubular element.